This invention relates to compositions comprising at least one polymer and at least one antistatic agent. This invention further relates to fibers, films, fabrics, coatings, and molded or blown articles comprising the compositions. In other aspects, this invention also relates to novel compounds that are useful as antistatic agents and to processes for imparting antistatic characteristics to substrates.
Electrostatic charge buildup is responsible for a variety of problems in the processing and use of many industrial products and materials. Electrostatic charging can cause materials to stick together or to repel one another. This is a particular problem in fiber and textile processing. In addition, static charge buildup can cause objects to attract dirt and dust, which can lead to fabrication or soiling problems and can impair product performance.
Sudden electrostatic discharges from insulating objects can also be a serious problem. With photographic film, such discharges can cause fogging and the appearance of artifacts. When flammable materials are present, a static electric discharge can serve as an ignition source, resulting in fires and/or explosions.
Static is a particular problem in the electronics industry, since modern electronic devices are extremely susceptible to permanent damage by static electric discharges. The buildup of static charge on insulating objects is especially common and problematic under conditions of low humidity and when liquids or solids move in contact with one another (tribocharging).
Static charge buildup can be controlled by increasing the electrical conductivity of a material. This can be accomplished by increasing ionic or electronic conductivity. The most common means of controlling static accumulation today is by increasing electrical conductivity through moisture adsorption. This is commonly achieved by adding moisture to the surrounding air (humidification) or by use of hygroscopic antistatic agents, which are generally referred to as humectants since they rely on the adsorption of atmospheric moisture for their effectiveness. Most antistatic agents operate by dissipating static charge as it builds up; thus, static decay rate and surface conductivity are common measures of the effectiveness of antistatic agents.
Antistatic agents can be applied to the surface (external antistat) or incorporated into the bulk (internal antistat) of an otherwise insulating material. Internal antistats are commonly employed in polymers such as plastics. Generally, internal antistats are mixed directly into a molten polymer during melt processing. (Typical polymer melt processing techniques include molding, melt blowing, melt spinning, and melt extrusion.) Relatively few antistatic agents have the requisite thermal stability to withstand polymer melt processing temperatures, which can be as high as 250 to 400xc2x0 C. or more. Since static buildup is typically a surface phenomenon, internal antistats that are capable of migrating to and enriching the surface of a material are generally most effective.
Known antistatic agents cover a broad range of chemical classes, including organic amines and amides, esters of fatty acids, organic acids, polyoxyethylene derivatives, polyhydridic alcohols, metals, carbon black, semiconductors, and various organic and inorganic salts. Many are also surfactants and can be neutral or ionic in nature.
Many low molecular weight, neutral antistats have sufficiently high vapor pressures that they are unsuitable for use at high temperatures, as in polymer melt processing, due to material losses that occur via evaporation. Many other neutral antistats have insufficient thermal stability to survive polymer melt processing or other high temperature processing conditions.
Most nonmetallic antistats are humectants that rely on the adsorption and conductivity of water for charge dissipation. Thus, their effectiveness is typically diminished at low atmospheric humidity. Since many of these antistatic agents are also water soluble, they are easily removed by exposure of the material to water (as in washing) and are therefore not very durable. Water associated with hygroscopic antistatic agents can be a particular problem during polymer melt processing, since the water tends to vaporize rapidly at melt processing temperatures. This leads to the undesirable formation of bubbles in the polymer and can cause screw slippage in extrusion equipment.
Quaternary ammonium salts are well known in the art to be useful antistatic agents. They can be solid or liquid, the most common being halide or methanesulfonate salts. The salts provide excellent antistatic performance but suffer from limited thermal stability and are generally hygroscopic. Thus, they are not capable of withstanding the high temperature processing conditions required for many high performance thermoplastic resins.
Metal salts of inorganic, organic, and fluoroorganic anions have also shown proven utility as antistatic agents in certain polymer compositions. Alkali metal salts are most commonly employed, due to cost and toxicity considerations and to the high affinity of alkali metal cations, especially lithium, for water. However, most metal salts provide insufficient thermal stability under high temperature processing conditions and are not compatible with polymers of moderate to low polarity, such as polypropylene, polyester, and polycarbonate. This incompatibility can result in inadequate antistat performance and/or an unacceptable reduction in physical properties or transparency in a finished polymeric article. Consequently, the utility of metal salts as internal antistatic agents is generally limited to highly polar and/or hydrophilic polymer matrices cast from aqueous or organic solution at relatively low temperatures.
Furthermore, since many metal salts are corrosive towards metals and electronic components, they are unsuitable for applications where they may come into contact with such surfaces. Known hydrophilic metal salts and quaternary ammonium salts generally suffer all the disadvantages of other humectant antistatic agents (vide supra).
Thus, there remains a need in the art for antistatic agents that exhibit a superior balance of high thermal stability, hydrophobicity, low volatility, low corrosivity toward metals and electronic components, durability, and polymer compatibility, and that can impart good antistatic performance to a variety of insulating materials over a wide range of humidity levels.
Briefly, in one aspect, this invention provides an antistatic composition comprising or consisting essentially of a melt blend of (a) at least one ionic salt consisting of a nonpolymeric nitrogen onium cation (for example, a quaternary ammonium ion) and a weakly coordinating fluoroorganic anion, the conjugate acid of the anion being a superacid (for example, a bis(perfluoroalkanesulfonyl)imide ion); and (b) at least one thermoplastic polymer. As used herein, the term xe2x80x9cmelt blendxe2x80x9d means a blend that has been prepared by melt processing technique(s), and the term xe2x80x9coniumxe2x80x9d means a positively charged ion having at least part of its charge localized on at least one nitrogen atom. Preferably, the Hammett acidity function, H0, of the conjugate acid of the anion is less than about xe2x88x9210.
It has been discovered that the above-described ionic salts can be used as additives (internal antistats) or topical treatments (external antistats) to impart antistatic characteristics to polymers or other insulating materials. These ionic salts are surprisingly effective at dissipating the static charge that can accumulate in an otherwise insulating substrate such as a polymer film or fabric. For example, when incorporated as polymer melt additive in polypropylene melt-blown nonwoven fabric, certain preferred salts impart static dissipation rates that are as good or better than those of any known antistatic agents under the same static decay test conditions. The ionic salts used in the composition of the invention are effective, even without the presence of a conductivity enhancing additive (for example, a lithium salt or a polar organic solvent), and thus compositions consisting essentially of salt and insulating material surprisingly exhibit good antistatic characteristics.
In addition, the ionic salts used in the composition of the invention exhibit surprisingly high thermal stabilities. The salts (surprisingly, even the quaternary ammonium salts) remain stable at temperatures up to 300-500xc2x0 C. (often, and preferably, at temperatures greater than 350xc2x0 C.) and thus are particularly well-suited for use as polymer melt additives (incorporated in host polymer through high temperature melt processing) and in applications where the use temperatures are very high. The salts are also nonvolatile (having essentially no vapor pressure), nonflammable, and can be utilized under normal processing and use conditions without the emission of potentially harmful vapors and without the gradual declines in antistat performance that result from evaporative loss.
The ionic salts used in the composition of the invention are compatible with a variety of polymers. Many of the salts are also hydrophobic (immiscible with water), and thus their antistatic performance is relatively independent of atmospheric humidity levels and durable even under exposure to aqueous environments. Preferred ionic salts are liquid at room temperature (for example, at about 25xc2x0 C.) and above.
The ionic salts used in the composition of the invention therefore meet the need in the art for antistatic agents that exhibit a superior balance of high thermal stability, hydrophobicity, low volatility, durability, and polymer compatibility, while imparting good antistatic performance to a variety of insulating materials over a wide range of humidity levels.
In other aspects, this invention also provides fiber, fabric, film, a coating, and a molded or blown article comprising the composition of the invention; novel compounds useful as antistatic agents; and processes for imparting antistatic characteristics to a substrate, for example, by bulk addition or by topical treatment.
Ionic salts suitable for use in the antistatic composition of the invention are those that consist of a nonpolymeric nitrogen onium cation and a weakly coordinating fluoroorganic (either fully fluorinated, that is perfluorinated, or partially fluorinated) anion. The nitrogen onium cation can be cyclic (that is, where the nitrogen atom(s) of the cation are ring atoms) or acyclic (that is, where the nitrogen atom(s) of the cation are not ring atoms but can have cyclic substituents). The cyclic cations can be aromatic, unsaturated but nonaromatic, or saturated, and the acyclic cations can be saturated or unsaturated.
The cyclic cations can contain one or more ring heteroatoms other than nitrogen (for example, oxygen or sulfur), and the ring atoms can bear substituents (for example, hydrogen, halogen, or organic groups such as alkyl, alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralkyl, aralicyclic, and alicyclicaryl groups). Separate alkyl substituents can be joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on nitrogen. Organic substituents can contain one or more heteroatoms such as, for example, nitrogen, oxygen, sulfur, phosphorus, or halogen (and thus can be fluoroorganic in nature).
The acyclic cations can have at least one (preferably, at least two; more preferably, at least three; most preferably, four) nitrogen-bonded organic substituents or R groups, with the remaining substituents being hydrogen. The R groups can be cyclic or acyclic, saturated or unsaturated, aromatic or nonaromatic, and can contain one or more heteroatoms such as, for example, nitrogen, oxygen, sulfur, phosphorus, or halogen (and thus can be fluoroorganic in nature).
Preferably, the nitrogen onium cation is acyclic, saturated cyclic, or aromatic. More preferably, the cation is acyclic or aromatic. Most preferably, the cation is aromatic for stability reasons.
Preferred acyclic nitrogen onium cations are quaternary or tertiary (most preferably, quaternary) ammonium ions. The quaternary and tertiary ammonium ions are preferably of low symmetry (having at least two, preferably at least three, different nitrogen-bonded organic substituents or R groups as defined above) and more preferably contain at least one hydroxyl group in at least one nitrogen-bonded organic substituent. Most preferred acyclic nitrogen onium cations are those described below for the ionic salts of Formula I.
Preferred aromatic nitrogen onium cations are those selected from the group consisting of 
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of H, F, alkyl groups of from 1 to about 4 carbon atoms, two said alkyl groups joined together to form a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N, and phenyl groups; and wherein said alkyl groups, alkylene radicals, or phenyl groups can be substituted with one or more electron withdrawing groups (preferably selected from the group consisting of Fxe2x80x94, Clxe2x80x94, CF3xe2x80x94, SF5xe2x80x94, CF3Sxe2x80x94, (CF3)2CHSxe2x80x94, and (CF3)3CSxe2x80x94).
More preferred aromatic cations include those selected from the group consisting of 
where R1, R2, R3, R4, and R5 are as defined above.
The weakly coordinating anion is a fluoroorganic anion, the conjugate acid of which is a superacid (that is, an acid that is more acidic than 100 percent sulfuric acid). Preferably, the Hammett acidity function, H0, of the conjugate acid of the anion is less than about xe2x88x9210 (more preferably, less than about xe2x88x9212). Such weakly coordinating fluoroorganic anions include those that comprise at least one highly fluorinated alkanesulfonyl group, that is, a perfluoroalkanesulfonyl group or a partially fluorinated alkanesulfonyl group wherein all non-fluorine carbon-bonded substituents are bonded to carbon atoms other than the carbon atom that is directly bonded to the sulfonyl group (preferably, all non-fluorine carbon-bonded substituents are bonded to carbon atoms that are more than two carbon atoms away from the sulfonyl group).
Preferably, the anion is at least about 80 percent fluorinated (that is, at least about 80 percent of the carbon-bonded substituents of the anion are fluorine atoms). More preferably, the anion is perfluorinated (that is, fully fluorinated, where all of the carbon-bonded substituents are fluorine atoms). The anions, including the preferred perfluorinated anions, can contain one or more catenary (that is, in-chain) heteroatoms such as, for example, nitrogen, oxygen, or sulfur.
Suitable weakly coordinating anions include, but are not limited to, anions selected from the group consisting of perfluoroalkanesulfonates, cyanoperfluoroalkanesulfonylamides, bis(cyano)perfluoroalkanesulfonylmethides, bis(perfluoroalkanesulfonyl)imides, bis(perfluoroalkanesulfonyl)methides, and tris(perfluoroalkanesulfonyl)methides.
Preferred anions include perfluoroalkanesulfonates, bis(perfluoroalkanesulfonyl)imides, and tris(perfluoroalkanesulfonyl)methides. The bis(perfluoroalkanesulfonyl)imides and tris(perfluoroalkanesulfonyl)methides are more preferred anions, with the bis(perfluoroalkanesulfonyl)imides being most preferred.
The ionic salts can be solids or liquids under use conditions but preferably have melting points less than about 150xc2x0 C. (more preferably, less than about 50xc2x0 C.; most preferably, less than about 25xc2x0 C.). Liquid ionic salts are preferred due to their generally better static dissipative performance. The ionic salts are preferably stable at temperatures of about 325xc2x0 C. and above (more preferably, about 350xc2x0 C. and above). (In other words, the onset of decomposition of the salts is above such temperatures.) The salts are also preferably hydrophobic. Thus, a preferred class of ionic salts for use in the antistatic composition of the invention includes those that consist of (a) an aromatic nitrogen onium cation selected from the group consisting of 
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of H, F, alkyl groups of from 1 to about 4 carbon atoms, two said alkyl groups joined together to form a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N, and phenyl groups; and wherein said alkyl groups, alkylene radicals, or phenyl groups can be substituted with one or more electron withdrawing groups (preferably selected from the group consisting of Fxe2x80x94, Clxe2x80x94, CF3xe2x80x94, SF5xe2x80x94, CF3Sxe2x80x94, (CF3)2CHSxe2x80x94, and (CF3)3CSxe2x80x94); and (b) a weakly coordinating fluoroorganic anion in accordance with the above description or a weakly coordinating anion selected from the group consisting of BF4xe2x80x94, PF6xe2x80x94, AsF6xe2x80x94, and SbF6xe2x80x94. This preferred class comprises a subclass of the hydrophobic ionic liquids described in U.S. Pat. No. 5,827,602 (Koch et al.), the description of the members of which is incorporated herein by reference.
Another preferred class of ionic salts useful in preparing the antistatic composition of the invention is the class of novel compounds represented by Formula I below
(R1)4xe2x88x92zN+[(CH2)qOR2]zXxe2x88x92xe2x80x83xe2x80x83(I)
wherein each R1 is independently selected from the group consisting of alkyl, alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralkyl, aralicyclic, and alicyclicaryl moieties that can contain one or more heteroatoms such as, for example, nitrogen, oxygen, sulfur, phosphorus, or halogen (and thus can be fluoroorganic in nature); each R2 is independently selected from the group consisting of hydrogen and the moieties described above for R1; z is an integer of 1 to 4; q is an integer of 1 to 4; and Xxe2x88x92 is a weakly coordinating fluoroorganic anion as described above. R1 is preferably alkyl, and R2is preferably selected from the group consisting of hydrogen, alkyl, and acyl (more preferably, hydrogen or acyl; most preferably, hydrogen).
The above-described ionic salts that are useful in the antistatic composition of the invention can be prepared by ion exchange or metathesis reactions, which are well known in the art. For example, a precursor onium salt (for example, an onium halide, onium alkanesulfonate, onium alkanecarboxylate, or onium hydroxide salt) can be combined with a precursor metal salt or the corresponding acid of a weakly coordinating anion in aqueous solution. Upon combining, the desired product (the onium salt of the weakly coordinating anion) precipitates (as a liquid or solid) or can be preferentially extracted into an organic solvent (for example, methylene chloride). The product can be isolated by filtration or by liquid/liquid phase separation, can be washed with water to completely remove by product metal halide salt or hydrogen halide, and can then be dried thoroughly under vacuum to remove all volatiles (including water and organic solvent, if present). Similar metathesis reactions can be conducted in organic solvents (for example, acetonitrile) rather than in water, and, in this case, the salt by product preferentially precipitates, while the desired product salt remains dissolved in the organic solvent (from which it can be isolated using standard experimental techniques). A few of the ionic salts (for example, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, available from Sigma Aldrich, Milwaukee, Wis.) are commercially available.
Precursor salts or acids (for use in preparing the ionic salts) can be prepared by standard methods known in the art, and many are commercially available. Such methods include the anion precursor preparative methods described in the following references, the descriptions of which are incorporated herein by reference: imide precursorsxe2x80x94U.S. Pat. No. 5,874,616 (Howells et al.), U.S. Pat. No. 5,723,664 (Sakaguchi et al.), U.S. Pat. No. 5,072,040 (Armand), and U.S. Pat. No. 4,387,222 (Koshar); methide precursorsxe2x80x94U.S. Pat. No. 5,554,664 (Lamanna et al.) and U.S. Pat. No. 5,273,840 (Dominey); sulfonate precursorsxe2x80x94U.S. Pat. No. 5,176,943 (Wou), U.S. Pat. No. 4,582,781 (Chen et al.), U.S. Pat. No. 3,476,753 (Hanson), and U.S. Pat. No. 2,732,398 (Brice et al.); sulfonate, imide, and methide precursors having caternary oxygen or nitrogen in a fluorochemical groupxe2x80x94U.S. Pat. No. 5,514,493 (Waddell et al.); disulfone precursorsxe2x80x94R. J. Koshar and R. A. Mitsch, J. Org. Chem., 38, 3358 (1973) and U.S. Pat. No. 5,136,097 (Armand).
In general, cyano-containing methides and amides containing fluoroalkanesulfonyl groups can be prepared by the reaction of fluoroalkanesulfonyl fluorides, RfSO2F, with anhydrous malononitrile or cyanamide, respectively, in the presence of a non-nucleophilic base. This synthetic procedure is described in Scheme 1 of U.S. Pat. No. 5,874,616 (Howells et al.) for the preparation of bis(fluoroalkanesulfonyl)imides (the description of which is incorporated herein by reference) and involves the substitution of either malononitrile or cyanamide for the fluoroalkanesulfonamide. The resulting intermediate non-nucleophilic base cation-containing methide or amide salt can be converted to the desired cation salt (typically lithium) via standard metathesis reactions well known in the art.
Representative examples of useful ionic salts include octyldimethyl-2-hydroxyethylammonium bis(trifluoromethylsulfonyl)imide: [C8H17N+(CH3)2CH2CH2OHxe2x88x92N(SO2CF3)2], octyldimethyl-2-hydroxyethylammonium perfluorobutanesulfonate: [C8H17N+(CH3)2CH2CH2OHxe2x88x92OSO2C4F9], octyldimethyl-2-hydroxyethylammonium trifluoromethanesulfonate: [C8H17N+(CH3)2CH2CH2OHxe2x88x92OSO2CF3], octyldimethyl-2-hydroxyethylammonium tris(trifluoromethanesulfonyl)methide: [C8H17N+(CH3)2CH2CH2OHxe2x88x92C(SO2CF3)3], trimethyl-2-acetoxyethylammonium bis(trifluoromethylsulfonyl)imide: [(CH3)3N+CH2CH2OC(O)CH3xe2x88x92N(SO2CF3)2], trimethyl-2-hydroxyethylammonium bis(perfluorobutanesulfonyl)imide: [(CH3)3N+CH2CH2OHxe2x88x92N(SO2C4F9)2], triethylammonium bis(perfluoroethanesulfonyl)imide: [Et3N+Hxe2x88x92N(SO2C2F5)2], tetraethylammonium trifluoromethanesulfonate: [CF3SO3xe2x88x92+NEt4], tetraethylammonium bis(trifluoromethanesulfonyl)imide: [(CF3SO2)2Nxe2x88x92+NEt4], tetramethylammonium tris(trifluoromethanesulfonyl)methide: [(CH3)4N+xe2x88x92C(SO2CF3)3], tetrabutylammonium bis(trifluoromethanesulfonyl)imide: [(C4H9)4N+xe2x88x92N(SO2CF3)2], trimethyl-3-perfluorooctylsulfonamidopropylammonium bis(trifluoromethanesulfonyl)imide: [C8F17SO2NH(CH2)3N+(CH3)3xe2x88x92N(SO2CF3)2], 1-hexadecylpyridinium bis(perfluoroethanesulfonyl)imide: [n-C16H33-cyc-N+C5H5xe2x88x92N(SO2C2F5)2], 1-hexadecylpyridinium perfluorobutanesulfonate: [n-C16H33-cyc-N+C5H5xe2x88x92OSO2C4F9], 1-hexadecylpyridinium perfluorooctanesulfonate: [n-C16H33-cyc-N+C5H5xe2x88x92OSO2C8F17], n-butylpyridinium bis(trifluoromethanesulfonyl)imide: [n-C4H9-cyc-N+C5H5xe2x88x92N(SO2CF3)2], n-butylpyridinium perfluorobutanesulfonate: [n-C4H9-cyc-N+C5H5xe2x88x92OSO2C4F9], 1,3-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide: [CH3-cyc-(N+C2H2NCH)CH2CH3xe2x88x92N(SO2CF3)2], 1,3-ethylmethylimidazolium nonafluorobutanesulfonate: [CH3-cyc-(N+C2H2NCH)CH2CH3xe2x88x92OSO2C4F9], 1,3-ethylmethylimidazolium trifluoromethanesulfonate: [CH3-cyc-(N+C2H2NCH)CH2CH3xe2x88x92OSO2CF3], 1,3-ethylmethylimidazolium hexafluorophosphate: [CH3-cyc-(N+C2H2NCH)CH2CH3PF6xe2x88x92], 1,3-ethylmethylimidazolium tetrafluoroborate: [CH3-cyc-(N+C2H2NCH)CH2CH3BF4xe2x88x92], 1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1,2-dimethyl-3-propylimidazolium tris(trifluoromethanesulfonyl)methide, 1,2-dimethyl-3-propylimidazolium trifluoromethanesulfonyl perfluorobutanesulfonylimide, 1-ethyl-3-methylimidazolium cyanotrifluoromethanesulfonylamide, 1-ethyl-3-methylimidazolium bis(cyano)trifluoromethanesulfonylmethide, 1-ethyl-3-methylimidazolium trifluoromethanesulfonylperfluorobutanesulfonylimide, octyldimethyl-2-hydroxyethylammonium trifluoromethylsulfonylperfluorobutanesulfonylimide, 2-hydroxyethytrimethyl trifluoromethylsulfonylperfluorobutanesulfonylimide, 2-methoxyethyltrimethylammonium bis(trifluoromethanesulfonyl)imide octyldimethyl-2-hydroxyethylammonium bis(cyano)trifluoromethanesulfonylmethide, trimethyl-2-acetoxyethylammonium trifluoromethylsulfonylperfluorobutanesulfonylimide, 1-butylpyridinium trifluoromethylsulfonylperfluorobutanesulfonylimide, 2-ethoxyethyltrimethylammonium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, perfluoro-1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-2-methylpyrazolium perfluorobutanesulfonate, 1-butyl-2-ethylpyrazolium trifluoromethanesulfonate, N-ethylthiazolium bis(trifluoromethanesulfonyl)imide, N-ethyloxazolium bis(trifluoromethanesulfonyl)imide, and 1-butylpyrimidinium perfluorobutanesulfonylbis(trifluoromethanesulfonyl)methide, 1,3-ethylmethylimidazolium hexafluorophosphate, 1,3-ethylmethylimidazolium tetrafluoroborate, and mixtures thereof.
Preferred ionic salts include octyldimethyl-2-hydroxyethylammonium bis(trifluoromethylsulfonyl)imide: [C8H17N+(CH3)2CH2CH2OHxe2x88x92N(SO2CF3)2], octyldimethyl-2-hydroxyethylammonium perfluorobutanesulfonate: [C8H17N+(CH3)2CH2CH2OHxe2x88x92OSO2C4F9], octyldimethyl-2-hydroxyethylammonium trifluoromethanesulfonate: [C8H17N+(CH3)2CH2CH2OHxe2x88x92OSO2CF3], octyldimethyl-2-hydroxyethylammonium tris(trifluoromethanesulfonyl)methide: [C8H17N+(CH3)2CH2CH2OHxe2x88x92C(SO2CF3)3], trimethyl-2-acetoxyethylammonium bis(trifluoromethylsulfonyl)imide: [(CH3)3N+CH2CH2OC(O)CH3xe2x88x92N(SO2CF3)2], trimethyl-2-hydroxyethylammonium bis(perfluorobutanesulfonyl)imide: [(CH3)3N+CH2CH2OHxe2x88x92N(SO2C4F9)2], triethylammonium bis(perfluoroethanesulfonyl)imide: [Et3N+Hxe2x88x92N(SO2C2F5)2], tetraethylammonium trifluoromethanesulfonate: [CF3SO3xe2x88x92+NEt4], tetraethylammonium bis(trifluoromethanesulfonyl)imide: [(CF3SO2)2Nxe2x88x92+NEt4], tetramethylammonium tris(trifluoromethanesulfonyl)methide: [(CH3)4N+xe2x88x92C(SO2CF3)3], tetrabutylammonium bis(trifluoromethanesulfonyl)imide: [(C4H9)4N+xe2x88x92N(SO2CF3)2], trimethyl-3-perfluorooctylsulfonamidopropylammonium bis(trifluoromethanesulfonyl)imide: [C8F17SO2NH(CH2)3N+(CH3)3xe2x88x92N(SO2CF3)2], 1-hexadecylpyridinium bis(perfluoroethanesulfonyl)imide: [n-C16H33-cyc-N+C5H5xe2x88x92N(SO2C2F5)2], 1-hexadecylpyridinium perfluorobutanesulfonate: [n-C16H33-cyc-N+C5H5xe2x88x92OSO2C4F9], 1-hexadecylpyridinium perfluorooctanesulfonate: [n-C16H33-cyc-N+C5H5xe2x88x92OSO2C8F17], n-butylpyridinium bis(trifluoromethanesulfonyl)imide: [n-C4H9-cyc-N+C5H5xe2x88x92N(SO2CF3)2], n-butylpyridinium perfluorobutanesulfonate: [n-C4H9-cyc-N+C5H5xe2x88x92OSO2C4F9], 1,3-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide: [CH3-cyc-(N+C2H2NCH)CH2CH3xe2x88x92N(SO2CF3)2], 1,3-ethylmethylimidazolium nonafluorobutanesulfonate: [CH3-cyc-(N+C2H2NCH)CH2CH3xe2x88x92OSO2C4F9], 1,3-ethylmethylimidazolium trifluoromethanesulfonate: [CH3-cyc-(N+C2H2NCH)CH2CH3xe2x88x92OSO2CF3], 1,3-ethylmethylimidazolium tetrafluorobroate, and mixtures thereof.
More preferred ionic salts include 2-hydroxyethylammonium bis(trifluoromethylsulfonyl)imide, octyldimethyl-2-hydroxyethylammonium perfluorobutanesulfonate, octyldimethyl-2-hydroxyethylammonium trifluoromethanesulfonate, triethylammonium bis(perfluoroethanesulfonyl)imide, tetraethylammonium trifluoromethanesulfonate, trimethyl-3-perfluorooctylsulfonamidopropylammonium bis(trifluoromethanesulfonyl)imide, 1,3-ethylmethylimidazolium nonafluorobutanesulfonate, 1,3-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-ethylmethylimidazolium trifluoromethanesulfonate, and mixtures thereof.
Most preferred ionic salts include 2-hydroxyethylammonium bis(trifluoromethylsulfonyl)imide, octyldimethyl-2-hydroxyethylammonium trifluoromethanesulfonate, triethylammonium bis(perfluoroethanesulfonyl)imide, 1,3-ethylmethylimidazolium nonafluorobutanesulfonate, 1,3-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-ethylmethylimidazolium trifluoromethanesulfonate, and mixtures thereof, with further preferences being in accordance with the general cation and anion preferences set forth above.
Insulating materials that are suitable for topical treatment include materials that have relatively low surface and bulk conductivity and that are prone to static charge buildup. Such materials include both synthetic and naturally-occurring polymers (or the reactive precursors thereof, for example, mono- or multifunctional monomers or oligomers) that can be either organic or inorganic in nature, as well as ceramics, glasses, and ceramers (or the reactive precursors thereof).
Suitable synthetic polymers (which can be either thermoplastic or thermoset) include commodity plastics such as, for example, poly(vinyl chloride), polyethylenes (high density, low density, very low density), polypropylene, and polystyrene; engineering plastics such as, for example, polyesters (including, for example, poly(ethylene terephthalate) and poly(butylene terephthalate)), polyamides (aliphatic, amorphous, aromatic), polycarbonates (for example, aromatic polycarbonates such as those derived from bisphenol A), polyoxymethylenes, polyacrylates and polymethacrylates (for example, poly(methyl methacrylate)), some modified polystyrenes (for example, styrene-acrylonitrile (SAN) and acrylonitrile-butadiene-styrene (ABS) copolymers), high-impact polystyrenes (SB), fluoroplastics, and blends such as poly(phenylene oxide)-polystyrene and polycarbonate-ABS; high-performance plastics such as, for example, liquid crystalline polymers (LCPs), polyetherketone (PEEK), polysulfones, polyimides, and polyetherimides; thermosets such as, for example, alkyd resins, phenolic resins, amino resins (for example, melamine and urea resins), epoxy resins, unsaturated polyesters (including so-called vinyl esters), polyurethanes, allyllics (for example, polymers derived from allyldiglycolcarbonate), fluoroelastomers, and polyacrylates; and the like and blends thereof. Suitable naturally occurring polymers include proteinaceous materials such as silk, wool, and leather; and cellulosic materials such as cotton and wood.
Particularly useful insulating materials are thermoplastic polymers, including those described above, as such polymers can be used in preparing the antistatic composition of the invention. Preferably, the thermoplastic polymers are melt processable at elevated temperatures, for example, above about 150xc2x0 C. (more preferably, above about 250xc2x0 C.; even more preferably, above about 280xc2x0 C.; most preferably, above about 320xc2x0 C.). Preferred thermoplastic polymers include, for example, polypropylene, polyethylene, copolymers of ethylene and one or more alpha-olefins (for example, poly(ethylene-butene) and poly(ethylene-octene)), polyesters, polyurethanes, polycarbonates, polyetherimides, polyimides, polyetherketones, polysulfones, polystyrenes, ABS copolymers, polyamides, fluoroelastomers, and blends thereof. More preferred are polypropylene, polyethylene, polyesters, polyurethanes, polycarbonates, and blends thereof, with polypropylene, polycarbonates, polyesters, and blends thereof being most preferred.
The antistatic composition of the invention can generally be prepared by combining at least one ionic salt (alone or in combination with other additives) and at least one thermoplastic polymer and then melt processing the resulting combination. Alternative processes for preparing an antistatic composition include, for example, (a) combining at least one ionic salt (alone or in combination with other additives) and at least one thermosetting polymer or ceramer (or the reactive precursors thereof) and then allowing the resulting combination to cure, optionally with the application of heat or actinic radiation; (b) applying a treatment composition comprising at least one ionic salt to at least a portion of at least one surface of at least one insulating material; (c) dissolving at least one ionic salt and at least one insulating material in at least one solvent and then casting or coating the resulting solution and allowing evaporation of the solvent, optionally with the application of heat; and (d) combining at least one ionic salt (alone or in combination with other additives) and at least one monomer and then allowing polymerization of the monomer to occur, optionally in the presence of at least one solvent and optionally with the application of heat or actinic radiation.
To form a melt blend by melt processing, the ionic salt(s) can be, for example, intimately mixed with pelletized or powdered polymer and then melt processed by known methods such as, for example, molding, melt blowing, melt spinning, or melt extrusion. The salt(s) can be mixed directly with the polymer or they can be mixed with the polymer in the form of a xe2x80x9cmaster batchxe2x80x9d (concentrate) of the salt(s) in the polymer. If desired, an organic solution of the salt(s) can be mixed with powdered or pelletized polymer, followed by drying (to remove solvent) and then by melt processing. Alternatively, molten salt(s) can be injected into a molten polymer stream to form a blend immediately prior to, for example, extrusion into fibers or films or molding into articles.
After melt processing, an annealing step can be carried out to enhance the development of antistatic characteristics. In addition to, or in lieu of, such an annealing step, the melt processed combination (for example, in the form of a film or a fiber) can also be embossed between two heated rolls, one or both of which can be patterned. An annealing step typically is conducted below the melt temperature of the polymer (for example, in the case of polyamide, at about 150-220xc2x0 C. for a period of about 30 seconds to about 5 minutes). In some cases, the presence of moisture can improve the effectiveness of the ionic salt(s), although the presence of moisture is not necessary in order for antistatic characteristics to be obtained.
The ionic salt(s) can be added to thermoplastic polymer (or, alternatively, to other insulating material) in an amount sufficient to achieve the desired antistatic properties for a particular application. This amount can be determined empirically and can be adjusted as necessary or desired to achieve the antistatic properties without compromising the properties of the polymer (or other insulating material). Generally, the ionic salt(s) can be added in amounts ranging from about 0.1 to about 10 percent by weight (preferably, from about 0.5 to about 2 percent; more preferably, from about 0.75 to about 1.5 percent) based on the weight of polymer (or other insulating material).
In topical treatment of an insulating material, the ionic salt(s) can be employed alone or in the form of aqueous suspensions, emulsions, or solutions, or as organic solvent solutions, in the topical treatment of the insulating material. Useful organic solvents include chlorinated hydrocarbons, alcohols (for example, isopropyl alcohol), esters, ketones (for example, methyl isobutyl ketone), and mixtures thereof. Generally, the solvent solutions can contain from about 0.1 to about 50 percent, or even up to about 90 percent, by weight non-volatile solids (based on the total weight of the components). Aqueous suspensions, emulsions, or solutions are generally preferred and generally can contain a non-volatile solids content of about 0.1 to about 50 percent, preferably, about 1 to about 10 percent, by weight (based on the total weight of the components). Preferably, however, topical treatment is carried out by applying (to at least a portion of at least one surface of at least one insulating material) a topical treatment composition that consists essentially of at least one ionic salt that is liquid at the use or treatment temperature. Such a topical treatment process involves the use of the neat liquid ionic salt, without added solvent, and is thus preferred from an environmental perspective over the use of organic solvent solutions of ionic salt(s).
The liquid ionic salt(s) (or suspensions, emulsions, or solutions of liquid or solid ionic salt(s)) can be applied to an insulating material by standard methods such as, for example, spraying, padding, dipping, roll coating, brushing, or exhaustion (optionally followed by the drying of the treated material to remove any remaining water or solvent). The material can be in the form of molded or blown articles, sheets, fibers (as such or in aggregated form, for example, yarn, toe, web, or roving, or in the form of fabricated textiles such as carpets), woven and nonwoven fabrics, films, etc. If desired, the salt(s) can be co-applied with conventional fiber treating agents, for example, spin finishes or fiber lubricants.
The liquid ionic salts(s) (or suspensions, emulsions, or solutions of liquid or solid ionic salt(s)) can be applied in an amount sufficient to achieve the desired antistatic properties for a particular application. This amount can be determined empirically and can be adjusted as necessary or desired to achieve the antistatic properties without compromising the properties of the insulating material.
Any of a wide variety of constructions can be made from the antistatic composition of the invention, and such constructions will find utility in any application where some level of antistatic characteristic is required. For example, the antistatic composition of the invention can be used to prepare films and molded or blown articles, as well as fibers (for example, melt-blown or melt-spun fibers, including microfibers) that can be used to make woven and nonwoven fabrics. Such films, molded or blown articles, fibers, and fabrics exhibit antistatic characteristics under a variety of environmental conditions and can be used in a variety of applications.
For example, molded articles comprising the antistatic composition of the invention can be prepared by standard methods (for example, by high temperature injection molding) and are particularly useful as, for example, headlamp covers for automobiles, lenses (including eyeglass lenses), casings or circuit boards for electronic devices (for example, computers), screens for display devices, windows (for example, aircraft windows), and the like. Films comprising the antistatic composition of the invention can be made by any of the film making methods commonly employed in the art. Such films can be nonporous or porous (the latter including films that are mechanically perforated), with the presence and degree of porosity being selected according to the desired performance characteristics. The films can be used as, for example, photographic films, transparency films for use with overhead projectors, tape backings, substrates for coating, and the like.
Fibers comprising the composition of the invention can be used to make woven or nonwoven fabrics that can be used, for example, in making medical fabrics, medical and industrial apparel, fabrics for use in making clothing, home furnishings such as rugs or carpets, and filter media such as chemical process filters or respirators. Nonwoven webs or fabrics can be prepared by processes used in the manufacture of either melt-blown or spunbonded webs. For example, a process similar to that described by Wente in xe2x80x9cSuperfine Thermoplastic Fibers,xe2x80x9d Indus. Eng""g Chem. 48, 1342 (1956) or by Wente et al. in xe2x80x9cManufacture of Superfine Organic Fibers,xe2x80x9d Naval Research Laboratories Report No. 4364 (1954) can be used. Multi-layer constructions made from nonwoven fabrics enjoy wide industrial and commercial utility, for example, as medical fabrics. The makeup of the constituent layers of such multi-layer constructions can be varied according to the desired end-use characteristics, and the constructions can comprise two or more layers of melt-blown and spunbonded webs in many useful combinations such as those described in U.S. Pat. No. 5,145,727 (Potts et al.) and U.S. Pat. No. 5,149,576 (Potts et al.), the descriptions of which are incorporated herein by reference.
The ionic salts used in the antistatic composition of the invention can also find utility as additives to coatings (for example, polymer or ceramer coatings). Such coatings can be both antistatic and scratch-resistant and can be used in the photographic industry or as protective coatings for optical or magnetic recording media.
If desired, the antistatic composition of the invention can further contain one or more conventional additives commonly used in the art, for example, dyes, pigments, antioxidants, ultraviolet stabilizers, flame retardants, surfactants, plasticizers (for example, polymers such as polybutylene), tackifiers, fillers, and mixtures thereof.
Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention.
HTS 905Axe2x80x94Larostat(trademark) HTS 905A, C8H17N+(CH3)2CH2CH2OHxe2x88x92OSO2CH3, available from BASF, Gurnee, Ill.
HQ-115xe2x80x94LiN(SO2CF3)2 available from 3M, St. Paul, Minn.
PBSFxe2x80x94Perfluorobutanesulfonyl fluoride, available from Sigma-Aldrich, Milwaukee, Wis.
Lithium triflatexe2x80x94Lithium trifluoromethanesulfonate, available from Sigma-Aldrich, Milwaukee, Wis.
FC-24xe2x80x94Trifluoromethanesulfonic acid, available from 3M, St. Paul, Minn.
FC-754xe2x80x94Trimethyl-3-perfluorooctylsulfonamidopropylammonium chloride, available from 3M, St. Paul, Minn.
Aliquat(trademark) 336xe2x80x94Methyltrioctylammonium chloride, available from Sigma-Aldrich, Milwaukee, Wis., or from Henkel Corp., Ambler, Pa.
FC-94xe2x80x94Lithium perfluorooctanesulfonate, available from 3M, St. Paul, Minn.
Cetylpyridinium chloride monohydratexe2x80x941-Hexadecylpyridinium chloride, available from Research Organics, Cleveland, Ohio.
1,3-Ethylmethylimidazolium chloridexe2x80x94Available from Sigma-Aldrich, Milwaukee, Wis.
Silver triflatexe2x80x94Silver trifluoromethanesulfonate, available from Sigma-Aldrich, Milwaukee, Wis.
AgBF4xe2x80x94Silver tetrafluoroborate, available from Sigma-Aldrich, Milwaukee, Wis.
NH4PF6xe2x80x94Ammonium hexafluorophosphate, available from Sigma-Aldrich, Milwaukee, Wis.
Acetylcholine chloridexe2x80x94CH3CO2CH2CH2N(CH3)3Cl, available from Research Organics, Cleveland, Ohio.
Choline chloridexe2x80x94HOCH2CH2N(CH3)3Cl, available from Sigma-Aldrich, Milwaukee, Wis.
PP3505xe2x80x94ESCORENE(trademark) PP3505 polypropylene, having a 400 melt index flow rate, available from Exxon Chemical Co., Baytown, Tex.
PE6806xe2x80x94ASPUN(trademark) 6806 polyethylene, having a melt flow index of 105 g/10 min (as measured by Test Method ASTM D-1238) and having a peak melting point of 124.8xc2x0 C., available from Dow Chemical Co., Midland, Mich.
PS440-200xe2x80x94MORTHANE(trademark) PS440-200 urethane, available from Morton Thiokol Corp., Chicago, Ill.
PET 65-1000xe2x80x94polyethylene terephthalate available from the 3M Company, Decatur, Ala.
LQ-3147xe2x80x94Makrolon(copyright) LQ-3147 polycarbonate available from Bayer Corp., Pittsburg, Pa.
Mellinex 617xe2x80x94Melamine primed polyethylene terephthalate film (0.177 mm thick), available from DuPont, Hopewell, Va.
Test Method Ixe2x80x94Melting Point Determination
The melting points of salts were determined by differential scanning calorimetry (DSC) using a 20xc2x0 C. per minute temperature ramp. The peak maximum of the melt transition was taken as the melting point (Tm). Where multiple melt transitions were observed, the peak associated with largest area melt transition was taken as the melting point.
Test Method IIxe2x80x94Onset of Thermal Decomposition Determination
The onset of thermal decomposition of each salt was determined by thermal gravimetric analysis (TGA) under an inert nitrogen atmosphere using a 10xc2x0 C. per minute temperature ramp. The value of the onset temperature was determined by finding the intersection of the extrapolated tangent at the baseline preceding onset and the extrapolated tangent at the inflection point associated with the step change in sample weight.
Test Method IIIxe2x80x94Static Charge Dissipation Test
The static charge dissipation characteristics of nonwoven fabrics, films, and molded sheets were determined with this method. The test materials were cut into 9 cm by 12 cm samples and conditioned at relative humidities (RH) of about 10 percent, 25 percent, and 50 percent for at least 12 hours. The materials were tested at temperatures that ranged from 22-25xc2x0 C. The static charge dissipation time was measured according to Federal Test Method Standard 10113, Method 4046, xe2x80x9cAntistatic Properties of Materialsxe2x80x9d, using an ETS Model 406C Static Decay Test Unit (manufactured by Electro-Tech Systems, Inc., Glenside, Pa.). This apparatus induces an initial static charge (Average Induced Electrostatic Charge) on the surface of the flat test material by using high voltage (5000 volts), and a fieldmeter allows observation of the decay time of the surface voltage from 5000 volts (or whatever the induced electrostatic charge was) to 10 percent of the initial induced charge. This is the static charge dissipation time. The lower the static charge dissipation time, the better the antistatic properties are of the test material. All reported values of the static charge dissipation times in this invention are averages (Average Static Decay Rate) over at least 3 separate determinations. Values reported as  greater than 60 sec indicate that the material tested has an initial static charge which cannot be removed by surface conduction and is not antistatic.
Test Method IVxe2x80x94Surface Resistivity Test
This test was conducted according to the procedure of ASTM Standard D-257, xe2x80x9cD.C. Resistance or Conductance of Insulating Materialsxe2x80x9d. The surface resistivity was measured under the conditions of this test method using an ETS Model 872 Wide Range Resistance Meter fitted with a Model 803B probe (Electro-Tech Systems, Inc., Glenside, Pa.). This apparatus applies an external voltage of 100 volts across two concentric ring electrodes contacting the flat test material, and provides surface resistivity readings in ohm/square units.
In the following where weight percent or parts by weight are indicated, these are basis on the weight of the entire composition unless indicated otherwise.
The title compound was prepared according to the method described in U.S. Pat. No. 5,874,616, Example 3, except that the procedure was terminated once the methylene chloride solvent was evaporated. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 2.
In a 2 L flask, 300 g of CF3SO3H (FC-24) was charged. The acid was neutralized by slow addition of about 800 g Et4NOH aqueous solution (35%) until the pH reached about 6. A white solid (560 g) was obtained after drying by rotary evaporation, then under high vacuum. The solid was re-crystallized from chloroform-heptane to give 520 g pure product. The product was also characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 2.
In a 1 L flask, 50 g of (CF3SO2)2Nxe2x88x92Li+ (HQ-115) was dissolved in 50 g of deionized water. The solution was combined with 89 g of 35% Et4NOH aqueous solution under N2. Solid precipitated during the addition, which was dissolved by the addition of 50 g CH2Cl2. The bottom organic layer was isolated. The aqueous solution was extracted with another 50 g of CH2Cl2. The combined organic solution was washed with water (2xc3x9725 mL), and volatiles were removed by rotary evaporation. Re-crystallization of the crude product from CH3OHxe2x80x94H2O gave 70 g of white solid after full vacuum drying. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 2.
The title compound was prepared according to the method of U.S. Pat. No. 5,554,664, Example 18, except that the procedure was terminated after line 55. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 2.
The title compound was prepared by reacting (C4H9)4N+Brxe2x88x92 (Sigma-Aldrich, Milwaukee, Wis.) with approximately a 10% molar excess of Li+xe2x88x92N(SO2CF3)2 (HQ-115) according to the procedure described in Example 18. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 2.
The title compound was prepared according to the method of Example 14, except that 85.1 g of Li+xe2x88x92N(SO2C2F5)2 (HQ-115) was employed as the anion precursor. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 3.
Cetylpyridinium chloride monohydrate (75 g) was dissolved in 800 ml water with gentle heating and magnetic stirring. To this solution was added 67.3 g of Li+xe2x88x92OSO2C4F9 (prepared by hydrolysis of C4F9SO2F [PBSF] with LiOH) dissolved in 600 mL of water with stirring. Product precipitated immediately and was isolated by suction filtration. The product was washed with copious amounts of water and then dried initially by suction and then in vacuo at 10xe2x88x922 Torr, 40xc2x0 C. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 3.
The title compound was prepared according to the method of Example 14, except that 111.3 g of Li+xe2x88x92OSO2C8F17 (FC-94) was employed as the anion precursor. The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 3.
A solution of 50 g Li+xe2x88x92N(SO2CF3)2 (HQ-115) (287 g/mol, 0.174 mol) and 100 ml DI water was prepared. Another solution of 30 g butylpyridinium chloride (171.6 g/mol, 0.174) and 100 ml DI water was prepared. The two solutions were added to a separatory funnel along with 200 ml methylene chloride. The mixture was thoroughly shaken, and the phases were allowed to separate. The organic phase was isolated and washed with 3xc3x97200 ml DI water. The organic layer was then concentrated by reduced pressure distillation on a rotary evaporator. The resulting yellow oil was vacuum dried at 120 C. overnight to afford 70 g product (97% yield). The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 3.
A solution of 20 g butylpyridinium chloride (171.6 g/mol, 0.116 mol) was made with 100 ml DI water. A similar solution was prepared using 35.7 g Li+xe2x88x92OSO2C4F9 (prepared by hydrolysis of C4F9SO2F [PBSF] with LiOH) (306 g/mol, 0.116 mol) and 100 ml water. The two solutions were added to a separatory funnel along with 200 ml methylene chloride. The mixture was thoroughly shaken, and the phases were allowed to separate. The organic phase was isolated and washed with 200 ml DI water. The mixture was slow to separate, consequently further washings were not done. The organic layer was concentrated by reduced pressure distillation on a rotary evaporator. It was then dried under vacuum at 130 C. overnight. The isolated yellow oil weighed 44 g (87% yield). The product was characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 3.
1,3-Ethylmethylimidazolium chloride (50.0 g) and LiN(SO2CF3)2 (HQ-115) (102.8 g) were combined in 500 mL of water with magnetic stirring. A nonmiscible light yellow oil of low viscosity separated as a lower liquid phase. The mixture was transferred to a separatory funnel combined with 500 mL of CH2Cl2 and the workup conducted essentially as described in Example 1. After vacuum stripping all volatiles, a total of 112.2 g (84% yield) of light yellow oil of high purity was obtained, which was identified as the title compound by 1H and 19F NMR. The product was also characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 4.
1,3-Ethylmethylimidazolium chloride (49.1 g) and LiOSO2C4F9 (107.6 g, prepared by hydrolysis of C4F9SO2F with LiOH) were combined in 500 mL of water with magnetic stirring. A homogeneous aqueous solution was formed, which was transferred to a separatory funnel, combined with 500 mL of CH2Cl2 and worked up according to the procedure in Example 1. After vacuum stripping all volatiles, a total of 65.0 g (47% yield) of light yellow oil of high purity was obtained, which was identified as the title compound by 1H and 19F NMR. The product was also characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 4.
1,3-Ethylmethylimidazolium chloride (29 g, 0.199 mole) was dissolved in 100 ml of water and added to solution of 50 g silver triflate (0.195 mol) in 200 g water with stirring. The silver chloride precipitate was removed by filtration, and the solids were washed with 100 ml of deionized water. The filtrate was concentrated on a rotary evaporator and further dried at 75xc2x0 C. overnight to provide 47.5 g of a light green oil that was characterized by 1H and 19F NMR. The product was also characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 4.
Separate solutions of 49.6 g AgBF4 (194.68 g/mol, 0.255 mol) in 200 ml distilled water, and 37.35 g 1,3-Ethylmethylimidazolium chloride (146.62 g/mol, 0.255 mol) in 200 ml distilled water were prepared. The two solutions were mixed together, instantly forming a white precipitate. The solution was allowed to settle, followed by filtration through a D-frit. The filtrate was concentrated, but not to dryness and allowed to stand at room temperature overnight. The next morning a black precipitate was observed to have fallen out of solution. The solution was passed through filter paper to removed the small amount of solid. The remaining water was removed by reduced pressure distillation on a rotary evaporator. The remaining oil was dissolved in 200 ml acetonitrile. More insoluble black precipitate was formed and was filtered out of the solution. The yellow filtrate was concentrated on the rotary evaporator, and the resulting oil was dried overnight under vacuum at 75 C. The isolated weight of product was 40 g (79% yield). The product was also characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 4.
A solution of 500 ml acetonitrile and 73.1 g 1,3-Ethylmethylimidazolium chloride (146.6 g/mol, 0.498 mol) was prepared in a 1 L flask. Another solution of 250 ml acetonitrile and 81.1 g NH4PF6 (163 g/mol, 0.498 mol) was similarly prepared and added to the former solution. A white precipitate instantly formed on mixing of the two solutions. The flask was chilled to near 0xc2x0 C. for 1 hour followed by filtration through high purity Celite using a D-frit. The solvent was removed by reduced pressure distillation on a rotary evaporator. The ionic salt was dried under vacuum at 75 C. overnight. The isolated weight of product was 114 g (89% yield). The product was also characterized for melting point (Tm) according to Test Method I and for onset of thermal decomposition (Td) according to Test Method II. Results are shown in Table 4.